JPH067347A - X-ray tomographic system - Google Patents

Abstract

PURPOSE:To exactly mark a photographic cross section to an examinee body even when the diameter of the examinee body is changed by making visible light for marking and X rays incident through the same passage on the examinee body at an optical device (marker) to optically instruct the cross section on the examinee body. CONSTITUTION:In the case of performing X-ray tomography, first of all, the photographic cross section is marked and for this marking, however, visible laser beams are irradiated from a laser light source 8. This visible laser beam is guided through a half mirror 9 and a reflection mirror 10 to a reflecting plane 7a of an X-ray transmission window 7, reflected several times between the mirrors 9 and 10, and afterwards, passed through a slit 12 between shielding members 11a and 11b, and the surface of an examinee body is irradiated with the laser beam. Next, a top panel or the like is moved so as to be coincident with the mark formed like this, and the examinee body is positioned. Afterwards, thermal electron is radiated from a filament 4 while rotating a rotary cathode 3 and collided to an anode 2, and the beams radiated from the anode 3 is similarly made incident through the slit 12 on the examinee body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to X-ray tomography including an optical device (hereinafter referred to as a marker) for optically pointing a tomographic plane on a subject when performing tomography on the subject. The present invention relates to an apparatus, and more particularly to a marker for an X-ray tomography apparatus including a rotating cathode X-ray tube.

[0002]

2. Description of the Related Art At present, an X-ray tomography apparatus which is widely used has an X-ray tube and an X-ray detector which are opposed to each other with a subject being interposed therebetween, and the X-ray tube and the X-ray detector are disposed around the subject. Are synchronized with each other, X-rays are emitted from the entire circumference of the subject, and a tomographic image of the region of interest is obtained. Such an X-ray tomography apparatus is provided with a marker for instructing an imaging cross section before actual tomography.

In the above-mentioned marker of the popular X-ray tomography apparatus, a visible light laser light source for the marker is arranged in parallel on the X-ray tube, and the X-ray tube and the laser light source are integrated before the tomography. It is configured so that the operator can confirm the imaging cross-section in advance by irradiating it with laser light around the subject.

[0004]

However, the conventional example having such a structure has the following problems. That is, the trajectory of the laser light emitted from the laser light source for the marker on the subject needs to be adjusted so as to match the trajectory of the X-ray on the subject. Since they are arranged side by side in the tube, the paths (irradiation angle) between the laser beam and the X-ray with respect to the region of interest of the subject are different. Therefore, for example, in the case of imaging the head of a subject, even if the locus of the laser beam and the locus of the X-ray are coincident with each other, another imaging region with a different cross-sectional diameter (for example,
When photographing (chest), there is a problem that the trajectory of the laser light and the trajectory of the X-ray do not match, and accurate marking cannot be performed.

In recent years, an X-ray tomography apparatus using a rotating cathode X-ray tube capable of high-speed tomography has been developed. In this X-ray tomography apparatus, a ring-shaped anode is fixedly installed in a ring-shaped vacuum container, a rotating cathode having a filament that emits thermoelectrons is arranged facing the anode, and the rotating cathode is magnetically levitated. By rotating at a high speed while performing the X-ray irradiation, X-rays are emitted from the entire circumference of the subject to enable high-speed tomography of a region of interest (for example, the heart). Such a high-speed X-ray tomography apparatus also requires a marker as in the above-described popular X-ray tomography apparatus, but if the laser light path and the X-ray path are different,
The same problem as described above occurs.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray tomography apparatus capable of accurately marking an X-ray tomography cross section.

[0007]

The present invention has the following constitution in order to achieve such an object. That is, the present invention relates to a rotation having an annular vacuum container, an annular anode fixedly installed in the vacuum container, and a thermionic emission unit that is arranged to face the anode and emits thermoelectrons toward the anode. An X-ray tomography apparatus including a cathode and an electromagnetic magnet mechanism for magnetically levitating and rotating the rotating cathode, which is attached to an inner peripheral surface of the vacuum container and allows X-rays emitted from the anode to pass therethrough. At the same time, an X-ray transmission window having a reflection surface that reflects incident visible light toward the inside of the vacuum container, a light source that is provided inside the vacuum container and emits visible light, and a visible light emitted from the light source. Optical means for guiding light to the reflection surface of the X-ray transmission window, and a material that is impermeable to X-rays and visible light.
A shield member having a slit along the inner peripheral surface of the vacuum container, which allows the X-rays transmitted through the linear transmission window and the visible light reflected by the reflection surface of the X-ray transmission window to pass toward the center side of the vacuum container. It is equipped with and.

[0008]

The operation of the present invention is as follows. While the rotating cathode is magnetically levitated and rotated by the electromagnetic magnet mechanism, thermoelectrons are emitted from the thermoelectron emitting portion of the rotating cathode. Since the thermoelectrons scan the annular anode in a circular shape, X-rays are emitted from the entire circumference from the anode toward the center of the vacuum container. This X-ray travels through the X-ray transmission window provided on the inner peripheral surface of the vacuum container and the slit of the shielding member toward the center of the vacuum container, and a tomographic image of the subject inserted in the center hole of the vacuum container is obtained. To be photographed. X like this
Prior to the line tomography, visible light is emitted from a light source to mark an imaging section. The visible light is guided to the reflecting surface of the X-ray transmission window by the optical means, is reflected by the reflecting surface, and then is irradiated onto the subject through the slit of the shielding member. As described above, since the X-ray and the visible light for marking go to the center of the vacuum container through the slit of the same shielding member, both of them pass through the same route, and the tomographic cross section is accurately marked. It

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view showing a schematic configuration of an X-ray tomography apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part, FIG. 3 is a view taken along the line AA of FIG. 2, and FIG. It is a figure which shows the example of arrangement | positioning of a marker.

In the figure, reference numeral 1 is an annular vacuum container made of stainless steel or the like, and a subject is inserted into the center hole of the vacuum container 1. An annular anode 2 made of, for example, tungsten is fixedly installed in the vacuum container 1. There is an annular rotating cathode 3 having a “T” -shaped cross section facing the anode 2, and a filament 4 as a thermionic emission portion is provided at a position facing the anode 2. On the outer peripheral surface of the vacuum container 1, a plurality of electromagnetic magnets 5 for magnetically levitating the rotating cathode 3 and a stator 6 for rotationally driving the rotating cathode 3 are provided at appropriate intervals.
The electromagnetic magnet 5 and the stator 6 correspond to the electromagnetic magnet mechanism in this invention.

An annular X-ray transmission window 7 made of an X-ray transmission material such as aluminum is fitted on the inner peripheral wall of the vacuum container 1. The inner peripheral surface of the X-ray transmission window 7 is formed with a groove formed in a "U" shape, and the surface of the groove is mirror-finished to form a reflection surface 7a for visible light. A laser light source 8 for irradiating a visible laser light for marking is arranged near the inner peripheral wall of the vacuum container 1. At the position below the X-ray transmission window 7, the laser light source 8
The visible laser light emitted from the
A half mirror 9 and a reflection mirror 10 as optical means for guiding to a are arranged opposite to each other. Half mirror 9
Inside the reflection mirror 10, annular shield members 11a and 11b made of a material that is impermeable to X-rays and visible laser light, for example, stainless steel or lead, are arranged so as to face each other. A slit 12 that allows passage of X-rays and visible laser light is formed between the members 11a and 11b.

Reference numeral E1 in FIG. 1 is a filament 4
A power source for supplying power to the device, reference numeral E2 is a DC high voltage power source for applying a DC high voltage between the anode 2 and the rotating cathode 3.

Next, the operation of the X-ray tomography apparatus having the above structure will be described. First, before performing X-ray tomography,
Mark the cross section. That is, as shown in FIG. 2, when visible laser light is emitted from the laser light source 8, the visible laser light passes through the half mirror 9 and the reflection mirror 1
Is reflected at 0 and guided to the reflection surface 7a of the X-ray transmission window 7,
Here, it is further reflected and goes to the mirrors 9 and 10. After being reflected several times between the mirrors 9 and 10 and the reflecting surface 7a,
The visible laser light passes through the gap below the mirrors 9 and 10,
Further, the light passes through the slit 12 between the shielding members 11a and 11b and irradiates the surface of the subject. As shown in FIG. 4, a marker composed of a laser light source 8, mirrors 9 and 10,
If it is installed at several places above the inner circumference of the vacuum container 1, the visible laser light emitted from each marker causes the top plate 2 to move.
A linear mark (a thin band of light) can be formed on the surface of the subject M placed on the surface of the object 0. The operator positions the subject M by moving the top plate 20 or the like so that the cross-sectional position of the region of interest to be imaged matches the mark.

When the marking of the radiographic section is completed as described above, the X-ray tomography is started. That is, the rotating cathode 3
While rotating, the thermoelectrons are emitted from the filament 4 and collide with the anode 2, thereby irradiating X-rays from the entire periphery of the subject M. The X-rays emitted from the anode 2 are transmitted through the X-ray transmission window 7, the gap between the mirrors 9 and 10, and the shielding member 11.
The light enters the subject M through the slit 12 between a and 11b, and a tomographic image of the region of interest is captured. Here, the visible laser light emitted from the laser light source 8 and the X-ray emitted from the anode 2 are slits 12 between the shielding members 11a and 11b formed of a material that is impermeable to the visible laser light and the X-ray. And enters the subject M. That is, since the visible laser light and the X-rays reach the subject M through the same path, even when imaging a region with a different cross-sectional diameter such as the head or chest of the subject M, the position marked with the visible laser light Therefore, X-rays will always be incident on, and therefore, the cross section of the subject marked with visible laser light is accurately imaged.

In the above embodiment, the X-ray tomography apparatus in which a plurality of markers are fixedly installed inside the vacuum container 1 has been described as an example, but the present invention is not limited to this. For example, as shown in FIG. 5, a movable housing 3 in which a laser light source 8, a half mirror 9 and a reflection mirror 10 are housed between the X-ray transmission window 7 and the shielding members 11a and 11b.
0 is attached so as to be rotatable along the inner peripheral surface of the vacuum container 1. A motor 31 is mounted on the housing 30, and the pinion 31 connected to the output shaft of the motor 31 is engaged with a rack 33 provided along the inner peripheral surface of the vacuum container 1. By driving the motor 31 in the forward and reverse directions, the laser light source 8 and the mirrors 9 and 10 reciprocally and swivelly move together with the housing 30 on the inner peripheral surface of the vacuum container 1. Can be marked.

[0016]

As is apparent from the above description, according to the present invention, the light emitted from the marker light source provided inside the vacuum container is reflected by the reflecting surface of the X-ray transmission window through the optical means. The light that is guided to and reflected by this reflective surface is
The subject is irradiated through the slits between the shielding members to mark the imaging cross section. On the other hand, during X-ray tomography, X-rays emitted from the anode pass through the X-ray transmission window, pass through the slit of the shielding member, and enter the subject. Since the shielding member is made of a material that is impermeable to X-rays and visible light, the visible light and X-rays for marking pass through only the slit of the shielding member and reach the subject.
Therefore, since the marking visible light and the X-rays enter the subject through the same path, even if the marking visible light and the X-rays have different diameters in the imaging cross section of the subject, such as the head and chest. It is possible to accurately mark the imaging cross section without the incident position on the subject being displaced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an X-ray tomography apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the main parts of the apparatus of the embodiment.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is a diagram showing an arrangement example of markers of the apparatus of the embodiment.

FIG. 5 is a sectional view showing a main part of a modified example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Anode 3 ... Rotating cathode 4 ... Electromagnetic magnet 6 ... Stator 7 ... X-ray transmission window 7a ... Reflection surface 8 ... Laser light source 9 ... Half mirror 10 ... Reflection mirror 11a, 11b ... Shielding member 12 ... Slit

Claims (1)

[Claims] 1. An annular vacuum container, an annular anode fixedly installed in the vacuum container, and arranged to face the anode,
In an X-ray tomography apparatus including a rotating cathode having a thermoelectron emitting portion for emitting thermoelectrons toward the anode, and an electromagnetic magnet mechanism for magnetically levitating the rotating cathode to drive the rotation, Provided inside the vacuum container, an X-ray transmission window that is attached to the peripheral surface and has a reflection surface that transmits the X-rays emitted from the anode and reflects incident visible light toward the inside of the vacuum container. A light source for emitting visible light, an optical means for guiding the visible light emitted from the light source to the reflection surface of the X-ray transmission window, and a material impermeable to X-rays and visible light, A slit is provided along the inner peripheral surface of the vacuum container for passing the X-rays transmitted through the X-ray transmission window and the visible light reflected by the reflection surface of the X-ray transmission window toward the center side of the vacuum container. With a shielding member X-ray tomography apparatus according to claim and.